Conjectures and counterexamples

To fully disprove a conjecture, one needs to find only ONE counterexample.

• True

• False

Which number is a counterexample to the following statement?
For all numbers a, 2a + 7 $\le17$  

• a = 6

• a = 0

• a = 5

• a = 1

Tags

CCSS.HSA.CED.A.1

CCSS.HSA.CED.A.3

CCSS.HSA.REI.B.3

Which of the following conjectures is false?

• The product of two even numbers is even.
• The sum of two even numbers is even.
• The product of two odd numbers is odd.
• The sum of two odd numbers is odd.

Tags

CCSS.6.EE.B.6

How many counters would come next?

• 5
• 7
• 9
• 11

Tags

CCSS.4.OA.C.5

How many squares are in Figure 4?

• 10

• 11

• 12

• 13

• 14

Tags

CCSS.5.G.B.3

CCSS.5.G.B.4

Find the next term in the sequence:
A, D, G, J, _____

• L
• M
• P
• K

Tags

CCSS.HSF.BF.A.2

Which of the following is the basis for inductive reasoning?

• definitions and accepted properties

• facts and rules

• laws of logic

• observed patterns

Tags

CCSS.4.OA.C.5

For a conjecture to be true, it must be true...

• in most cases.

• in all cases.

• on Thursday mornings.

• at least once.

Tags

CCSS.HSS.IC.A.1

If an animal is furry, then it is a hamster. What would be an appropriate counterexample?

• goldfish
• frog
• elephant
• cat

Tags

CCSS.HSS.CP.A.5

Find the next number in the sequence.
1, -1, 2, -2, 3, ___

• 4
• -4
• 3
• -3

Tags

CCSS.4.OA.C.5